1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * QNAP Turbo NAS Board power off. Can also be used on Synology devices.
4  *
5  * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
6  *
7  * Based on the code from:
8  *
9  * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
10  * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/serial_reg.h>
17 #include <linux/of.h>
18 #include <linux/io.h>
19 #include <linux/clk.h>
20 
21 #define UART1_REG(x)	(base + ((UART_##x) << 2))
22 
23 struct power_off_cfg {
24 	u32 baud;
25 	char cmd;
26 };
27 
28 static const struct power_off_cfg qnap_power_off_cfg = {
29 	.baud = 19200,
30 	.cmd = 'A',
31 };
32 
33 static const struct power_off_cfg synology_power_off_cfg = {
34 	.baud = 9600,
35 	.cmd = '1',
36 };
37 
38 static const struct of_device_id qnap_power_off_of_match_table[] = {
39 	{ .compatible = "qnap,power-off",
40 	  .data = &qnap_power_off_cfg,
41 	},
42 	{ .compatible = "synology,power-off",
43 	  .data = &synology_power_off_cfg,
44 	},
45 	{}
46 };
47 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
48 
49 static void __iomem *base;
50 static unsigned long tclk;
51 static const struct power_off_cfg *cfg;
52 
53 static void qnap_power_off(void)
54 {
55 	const unsigned divisor = ((tclk + (8 * cfg->baud)) / (16 * cfg->baud));
56 
57 	pr_err("%s: triggering power-off...\n", __func__);
58 
59 	/* hijack UART1 and reset into sane state */
60 	writel(0x83, UART1_REG(LCR));
61 	writel(divisor & 0xff, UART1_REG(DLL));
62 	writel((divisor >> 8) & 0xff, UART1_REG(DLM));
63 	writel(0x03, UART1_REG(LCR));
64 	writel(0x00, UART1_REG(IER));
65 	writel(0x00, UART1_REG(FCR));
66 	writel(0x00, UART1_REG(MCR));
67 
68 	/* send the power-off command to PIC */
69 	writel(cfg->cmd, UART1_REG(TX));
70 }
71 
72 static int qnap_power_off_probe(struct platform_device *pdev)
73 {
74 	struct device_node *np = pdev->dev.of_node;
75 	struct resource *res;
76 	struct clk *clk;
77 
78 	const struct of_device_id *match =
79 		of_match_node(qnap_power_off_of_match_table, np);
80 	cfg = match->data;
81 
82 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
83 	if (!res) {
84 		dev_err(&pdev->dev, "Missing resource");
85 		return -EINVAL;
86 	}
87 
88 	base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
89 	if (!base) {
90 		dev_err(&pdev->dev, "Unable to map resource");
91 		return -EINVAL;
92 	}
93 
94 	/* We need to know tclk in order to calculate the UART divisor */
95 	clk = devm_clk_get(&pdev->dev, NULL);
96 	if (IS_ERR(clk)) {
97 		dev_err(&pdev->dev, "Clk missing");
98 		return PTR_ERR(clk);
99 	}
100 
101 	tclk = clk_get_rate(clk);
102 
103 	/* Check that nothing else has already setup a handler */
104 	if (pm_power_off) {
105 		dev_err(&pdev->dev, "pm_power_off already claimed for %ps",
106 			pm_power_off);
107 		return -EBUSY;
108 	}
109 	pm_power_off = qnap_power_off;
110 
111 	return 0;
112 }
113 
114 static int qnap_power_off_remove(struct platform_device *pdev)
115 {
116 	pm_power_off = NULL;
117 	return 0;
118 }
119 
120 static struct platform_driver qnap_power_off_driver = {
121 	.probe	= qnap_power_off_probe,
122 	.remove	= qnap_power_off_remove,
123 	.driver	= {
124 		.name	= "qnap_power_off",
125 		.of_match_table = of_match_ptr(qnap_power_off_of_match_table),
126 	},
127 };
128 module_platform_driver(qnap_power_off_driver);
129 
130 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
131 MODULE_DESCRIPTION("QNAP Power off driver");
132 MODULE_LICENSE("GPL v2");
133